Accumulating snow expected Wednesday to Thursday

A clipper system will push into New Jersey on Wednesday afternoon, and could bring a mix of rain, ice, and snow through Thursday morning.

UPDATE as of 7 PM Tuesday...

I'm feeling a lot more comfortable and confident about the snow forecast tomorrow, thanks to the evening models converging much better than they have previously. Let's break out the bullet points:

• Still NOT a major winter storm.
• Timing remains the same as outlined below:
  • First snowflakes/raindrops around Noon on Wednesday.
  • Wednesday evening commute will be potentially messy (wintry and/or wet)
  • Last showers and sprinkles tapering off by daybreak on Thursday.
• Keeping this morning's forecast of maximum snow accumulations in the 1-3 inch range. We're now able to add some detail and clarity to where the heaviest snow totals will be. (Keep reading...)
• North Jersey will have the coldest air as the storm moves in, and thus would be the most likely to see snow (versus rain, wintry mix, etc.)
• South Jersey will have the most available moisture in the atmosphere. Additionally, the models have put the heaviest bands of precipitation and the most energy over the southern third of the state.
• Keeping that in mind, here is the latest snow forecast:
  • North of I-78: Light snow showers. Snow accumulations up to 1 inch.
  • Between I-78 and I-195: Mostly (if not all) snow, light to moderate in intensity. Snow accumulations of 1 to 2 inches.
  • South of I-195 (EXCEPT Coast): May start as wintry mix, transitioning over to snow, light to moderate in intensity. Snow accumulations of 2 to 3 inches.
  • Coastal Ocean, Atlantic, Cape May: May start as rain, transitioning over to snow. Intensity and totals here are a lingering question mark - as one model dramatically redevelops a low off the coast. For now, I'm going to stay conservative and realistic, call that one model run a fluke, and go with snow accumulations of 1 to 2 inches of snow here. But this part of the forecast in particular may need to be increased tomorrow.

So again, a little bit of snow might just be enough to give commuters and travelers a little bit of a headache for Wednesday and Thursday. A bigger headache might be coming this weekend, as a coastal system is expected to have some potentially wintry impacts for New Jersey... I'll have a closer look at the one tomorrow and through the rest of the week.

Original post from Tuesday morning

We are currently in the coldest period of the calendar year - literally the “dead of winter” - so it’s not really surprising that we have some snow in the forecast. Even though this will NOT be a major winter storm, there could still be accumulating snow and travel difficulties for both Wednesday and Thursday.

Storm Setup

An “Alberta clipper" system will arrive from the west as early as about Noon on Wednesday. With temperatures expected to be no higher than the mid 30s, that means snow will likely fall somewhere in the Garden State through the afternoon and evening. In warmer southern and coastal New Jersey, the precipitation may very well begin as rain or wintry mix.

This will set up a potentially messy Wednesday evening rush hour, as roads could be either icy, slushy, or wet. We all know that any of those three options would make driving treacherous.

From Wednesday evening to Thursday morning, light snow is expected to continue and eventually taper off.

Snow Accumulations

I’ve seen snow total forecasts for this storm as high as 9 inches. That is utterly ridiculous. Again, this is NOT a major storm. Our atmosphere is moisture starved. Temperatures will hover close enough to the freezing mark for part of the storm to warrant at least some mixing with rain. Our computer forecast models haven't even come close to settling on a prime storm track solution. And frankly, this clipper system just doesn't have a lot of "oomph" behind it.

My current forecast is for a broad 1 to 3 inches of snow accumulation across New Jersey.

I am not comfortable making a detailed snow forecast map at this time, because I don’t think anyone can really tell where the rain/snow line will end up and where the snow “bullseye” will be, given the current forecast information. The highest snow totals in the state could be in the Northwest (as usual), because it will be colder. Or the highest snow totals from this storm could be in South Jersey, as that’s where the majority of the moisture and the energy could end up.

Forecast Uncertainty

Every forecast every meteorologist ever makes has a degree of “confidence” or “uncertainty” - how comfortable and sure we are that a particular forecast will verify, given the available information. Communicating that uncertainty is very important to me as a forecaster - meteorology simply is not an exact science.

As you may have guessed by my language in this blog post and on the air, for a storm that’s only about 24 hours away, confidence for this storm is very low.

Allow me to visualize this for you. Computer forecast models are created every day, using complicated formulas and equations to make a well-educated “guess” at the weather forecast. Models are critical tool in a meteorologist’s arsenal to create accurate and timely forecasts. The three maps below show the forecast for total precipitation from around 1pm Wednesday through 1pm Thursday. Each map represents a different computer forecast model - the GFS, the NAM, and the SREF.

If you squint your eyes and focus on New Jersey, you can see that each model shows a drastically different solution. The GFS is the wettest at the moment, the NAM limits the precipitation to North and Central Jersey, and the SREF is the driest of the three. So my best option as an honest meteorologist is to say the “potential” is there for accumulating snow, and wait for the models to come into better agreement. It’s wisest to wait for more information to come in before popping higher snowfall totals… and ONLY if those higher snow totals are justified. (A lesson I learned from the great Alan Kasper, by the way.)

Recap

Here is the TL;DR recap of this forecast:

• This is NOT a major winter storm.
• Wintry weather is possible from lunchtime on Wednesday through Thursday morning.
• Best snow total forecast right now is a broad brush 1 to 3 inches across the entire state. Highest totals could be either in Northwest Jersey or South Jersey.
• Wednesday evening rush hour could be particularly messy. If accumulating snow happens in your town, Thursday morning could be icy and/or slushy as well.
• Confidence in this particular forecast is low.

We will, of course, continue to update this forecast on-air and online as we get closer to storm time on Wednesday. Want to know instantly when those updates are ready? Text WEATHER to 89000.